Strange Water Temp with Scangauge II

diesel_dog

Well-known member
Joined
May 17, 2006
Location
Jenkintown, Pa.
I have had a 99.5 golf for about a year and never had any problems with the water temp that I could tell. The idiot gauge points at 190 when warmed up as if it was nailed in place.

However I recently bough a scangauge and have one of the gauges set for water temp. Normally it reads between 180 - 190 however I have noticed some strange behavior recently. At times the scangauge temp will start to climb slowly. It seems to keep climbing up into the 250's while the idiot gauge says 190. What is really strange is that each time the scangauge updates the temp I can see that it first flashes a temp of around 185 for about a quarter second then goes to the higher number. Could the engine take that kind of temps without melting?

Am I dealing with a bad scangauge or a short? I do have a new temp sending unit but I dont really believe that is the problem.

Mark
 

c170b

Member
Joined
Mar 28, 2007
Location
Mid-Michigan
TDI
05 Jetta
diesel_dog said:
I have had a 99.5 golf for about a year and never had any problems with the water temp that I could tell. The idiot gauge points at 190 when warmed up as if it was nailed in place.

However I recently bough a scangauge and have one of the gauges set for water temp. Normally it reads between 180 - 190 however I have noticed some strange behavior recently. At times the scangauge temp will start to climb slowly. It seems to keep climbing up into the 250's while the idiot gauge says 190. What is really strange is that each time the scangauge updates the temp I can see that it first flashes a temp of around 185 for about a quarter second then goes to the higher number. Could the engine take that kind of temps without melting?

Am I dealing with a bad scangauge or a short? I do have a new temp sending unit but I dont really believe that is the problem.

Mark


I have a scangauge also: water temp on mine takes a long to come up. the gauge on the dash is like yours peged at 190.

mine just takes a long time to come up to temp...????? Scott
 

stancho

Veteran Member
Joined
Jul 25, 2006
Location
Schaumburg, IL
TDI
2002 Jetta GLS
Yeah, there is temp band within which the dashboard gauge shows 190. I've seen the water temp as high as 225 on my car. Maybe some of the more experienced voices will chime in as to what the normal operating temp range is.
 

jettawreck

Top Post Dawg
Joined
Aug 2, 2004
Location
Northern Minnesota-55744
TDI
2001 Jetta and 2003 Jetta
2001 Jetta w/ScanGauge I have never seen the temp over 185 and it was hot (mid 90F) this last month, but I drive rather conservatively. Anyways, dash temp gauge has a very "general" reading. (many describe it as a glorified idiot light) Mine will stay glued at 190 after warming up virtually no matter what. In fact, the dash gauge gets to 190 while ScanGauge is still climbing 170+ on the way to 181 where mine spends 99% of its time. I'm sure the gauge will give you a good general idea of whether the engine is cold, warm, operating temp, or HOT-but I wouldn't pay too much attention to the degree numbers on it. Scangauge may read temp from a different sensor than the dash, I do not know.
 

Phred

Active member
Joined
Mar 5, 2006
Location
Fort Collins, CO
TDI
2005 Golf
I noted the same behaviour on my 2005 Golf. While the dash indicator stayed pegged at 190F, during a hard climb in very hot weather, the ScanGaugeII read up to 205F, and backed down when I was done loading the engine.

My guess is that the ScanGaugeII is reading a more accurate tempurature that fluctuates with load, and the Dashboard gives a "normal" reading (midpoint at 190F) until things start getting really hot.

Interesting design descision by VW...
 

points

Well-known member
Joined
May 6, 2007
Location
Northern Twin Cities, MN
TDI
2003 Jetta
When I got the SGII my temp was reading 220-235. I knew something was wrong so I replaced the thermostat and the temp is at 202-205. The stock temp gauge is a joke.
 

Matthew_S

Veteran Member
Joined
Mar 19, 2006
Location
Renton/Redmond, WA
TDI
2002 Jetta GLS galactic blue
The temperature gauge will read 190 from approximately 170 to something just over 200 (220 maybe). Basically the gauge will show 190 when the engine is at normal operating temperature. VW knows that we can't handle the truth:rolleyes:

250 is way too hot. Try to get a different scanner (VAG-COM preferably) and see what it tells you.
 

phil B

Member
Joined
Nov 28, 2022
Location
Fairmont Hot Springs B.C.Canada
TDI
mkiv wagon
I Have a SG that reads high, and the dash gauge stays at 90°. The SG initially read 190°F,until the main(large)fan failed and was replaced. I've replaced the thermostat and temp. sensor. In the process of replacing the radiator temp sensor,and having my doubts. I've even unplugged and cleaned the plugs on the car and the ScanGauge. This issue is on a VW MKIV JETTA TDI WAGON.
 

Nuje

Top Post Dawg
Joined
Feb 11, 2005
Location
Island near Vancouver
TDI
2002 Golf 6MT; 2015 Sportwagen 6MT; 2016 A3 e-tron 6DSG
How high is "high"?
(You might want to stay consistent with your units, too - 90°C....what is the scan gauge reading in °C?)

For anyone interested in how/why the cluster shows 90°C / 190°F pretty much no matter what, here's a good explanation (and solution):
 

phil B

Member
Joined
Nov 28, 2022
Location
Fairmont Hot Springs B.C.Canada
TDI
mkiv wagon
I stand corrected,the thermal switch was changed yesterday.
The original temperature gauge on the cluster 'used' to take its time rising to 90°C. Now it definitely rises much quicker to 90°C and stays there.The SG temperature is in Fahrenheit. Will change it to Celsius tomorrow.
Thanks in advance.
 

Tuheeden

Veteran Member
Joined
Sep 18, 2022
Location
North Carolina
TDI
2013 & 2014 Jetta sportwagon
The idiot temp gauge will show 190f when the engine reaches low operating temperature of 167f. I have never seen the gauge show more even with coolant temperates above 235f.
Normal temperature is 185 to 210f but up to 220f under load is pretty common. If it's going above those numbers or below those numbers, I always change the thermostat and waalaa things go back to normal
 
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